You need to get at least 1 mw/mm^2 of light, so if you can get a LED pen that can do that, you can try it out. But you won’t have control on parameters like pulse-width, frequency, etc. The Thor system is pretty affordable. They’ve even got a very no frills starter kit:

A follow up. AAV1-hSyn-Cre from Penn. 1^13 vg/ml (10 ul) into the plantar hindpaw. Here is the spinal cord from this mouse at 4 weeks. Mostly very superficial DH with some deeper. I may have gotten a proprioceptor as well. Will need to use nuclear fluorophores to assess anterograde spread.

Awesome!It doesn’t look as good after RNAscope, presumably because of protease chewing up ribosomal proteins? Try 1:200 for 10 minutes. Extend the time if you want it darker. It’s not perfect after RNAscope but it’s not bad.

Translating Ribosome Affinity Purification (TRAP) in various DRG neurons
Back in 2014-2015, I was keen on trying to get TRAP to work in DRG. I tried with TRPV1-Cre and LSL-Rpl10a-EGFP mouse from Jax. There was labeling of the neurons, but the pulldowns for mRNA brought down a lot of nonspecific RNA and it was hard to see enrichment. Speaking to various other researchers who’ve used TRAP, this seems to be a common thread. So I abandoned the method. I do know that one group in the pain field has gotten TRAP to work on DRGs, so it’s not impossible. But it requires a lot of optimization.